1. Field of the Invention
The present invention relates to an apparatus and method for hydraulically removing and collecting cuttings from a cutting type machine tool.
2. Description of the Related Art
The operation of a machine tool inevitably leads to the production of cuttings from the material being machined. As a waste byproduct of the machining process, the cuttings must be removed from the area of the machine tool in order to prevent a buildup of cuttings which may hinder machine tool operation. Moreover, the cuttings become mixed with liquid coolant or lubricating oil used in the machine tool. In order not to waste the coolant or oil, it is desirable to separate out the cuttings so that the coolant or oil may be recycled.
As a first step in this disposal and separation process, the cuttings typically are collected in an area below the machine tool. In conventional systems, a perforated receptacle or tray may be positioned in this area to allow the liquid coolant or oil to drain off of the cuttings. See Hurlbut, U.S. Pat. No. 427,869 and Kitamura, U.S. Pat. No. 4,955,770. See also Thacher, U.S. Pat. No. 1,616,151.
In prior art systems, the cuttings are removed in a number of ways. The cuttings may be removed manually, e.g., by shoveling the cuttings from the cuttings tray. Another common method utilizes an auger to push the cuttings out of the trays. Alternatively, the chip conveyor method uses a steel belt instead of a cuttings tray or a collection receptacle. Cuttings fall onto the belt and are transported to a collection container. See Lopez, U.S. Pat. No. 4,679,295. The conveyor itself may be composed of a belt-like filter net material to allow the oil or coolant to drain off the cuttings into a collection pan. See Kitamura, U.S. Pat. No. 4,955,770.
In one conventional system, the chip conveyor apparatus has been combined with a drum in order to separate the cuttings from the coolant. See the Kleenall Chip Filter manufactured by Barnes International, Inc. In that apparatus, a conveyor consisting of a series of chain-driven angle bars is partially immersed in dirty coolant. Heavy chips at the bottom of the coolant tank are raked up an inclined side of the tank and through an exit hole by the moving angle bars. Meanwhile, coolant is filtered through a continuously turning drum, also partially immersed in the dirty coolant, which is rotated by the same chain that drives the conveyor. Small chips that were not removed by the conveyor are trapped in the nylon mesh surface of the drum. As the drum rotates, spray nozzles inside the drum continuously backwash the mesh material with coolant in order to dislodge the particles from the mesh surface. These particles accumulate and are carried away by the conveyor. Once filtered, the clean coolant passes out of the interior of the drum through an exit port.
These conventional methods present a number of disadvantages. First, the manual removal of cuttings is expensive because it is highly labor intensive. Second, the auger system is inefficient because it is subject to frequent jamming and because many cuttings do not fall within the range of the auger so that they may be pushed out of the cuttings trays.
Third, the chip conveyor system does not adequately separate the cuttings from the coolant. In theory, the conveyor belt transports the cuttings out from under the machine tool to a collection container as the cuttings fall off the belt. However, in practice, a large number of cuttings fall outside of the area of the conveying surface. Moreover, many cuttings typically do not fall off the belt but are instead transported back on the return travel of the belt during which the cuttings may fall off into the oil or coolant collection pan and again mix in with the oil or coolant. Moreover, the chip conveyor system is expensive to manufacture and utilizes many moving parts, thus requiring expensive maintenance.
Fourth, the combined drum/conveyor system is similarly complex and expensive to manufacture. The drum/conveyor apparatus unnecessarily requires separate components, i.e., the conveyor and the drum, to separate heavy cuttings and finer cuttings, respectively, from the coolant. As discussed below, the present invention avoids this degree of complexity, while providing superior separation of the cuttings from the coolant.